This invention relates generally to the art of syringes and more particularly to a syringe which reduces the likelihood of unintentional puncture or pricking of human skin. In recent history, the transmission of contagious diseases, particularly those brought about exclusively by the co-mingling of human body fluids, has been of great technological interest. One of the particular problems has been associated with the use and disposal of hypodermic syringes, particularly among healthcare professionals. There have been various devices developed for the destruction of the needles or cannula used in such syringes. Additional devices have been developed for capping of syringes which attempt to minimize the likelihood of accidental puncture. The accidental puncture or pricking of a finger, or any other part of the body, after the treatment of a patient with a contagious disease, particularly a deadly contagious disease, results in a high likelihood of transmission of that disease. Various syringes have been developed in the prior art to attempt to minimize the likelihood of accidental puncture after patient treatment.
One such device is described in U.S. Pat. No. 4,973,316 to Dysarz wherein a needle is retracted into the barrel of the syringe after the use thereof. Another such device is described in U.S. Pat. No. 4,921,486 to DeChellis, et al. One of the earlier patents in this regard was U.S. Pat. No. 2,460,039 issued to Scherer, et al.
Other references disclosing devices relating to needle retraction in a syringe include U.S. Pat. No. 4,994,034 to Botich et al, U.S. Pat. No. 4,838,869 to Allard, and U.S. Pat. No. 5,114,410 to Batlle, GB 2 197 792 to Powers et al., WIPO 90/06146 to Nacci et al., and WIPO 90/03196 to Utterberg et al. While all such devices seek the same goal of preventing accidental puncture, considerable room for improvement exists.
It is thus an object of this invention to provide a novel hypodermic syringe which minimizes the likelihood of accidental puncture.
It is a further object of this invention to provide such a syringe which, after utilization, isolates the used needle so as to render such needle harmless, and automatically indicates that the syringe represents a biohazard.
It is a further and more particular object of this invention to provide such a hypodermic syringe which is operable utilizing only one hand.
It is a further and yet more particular object of this invention to provide such a syringe which automatically, upon the end of an injection, retracts its needle to prevent its reuse, while sealing the needle within the body of the syringe to prevent leakage of residual fluids.
It is a further object of the invention to provide a simple device, which is manufacturable in high volumes.
These as well as other objects are accomplished by a hypodermic syringe having a barrel with a plunger movable therein to inject a fluid through a hollow needle thereof. A hollow needle is housed in a passageway within a needle assembly. Positioned between the passageway within the needle assembly and a shelf on an internal wall of the syringe barrel is a deformable base, with integral flexible supports. The deformable base forms a liquid tight seal with the barrel, at the needle end of the barrel. The deformable base houses an enlarged head of the needle which enlarged head is in contact with energy storage means within the passageway in the needle assembly. The plunger has a thin, rupturable web on an end thereof which is part of a boot covering the end of the plunger, the boot, including the web, being liquid impermeable for forcing a liquid from the barrel upon movement of the plunger. Upon completion of an injection, the boot-covered plunger contacts the deformable base, and upon application of force at the plunger, moves such base downward. Continued application of force causes the flexible supports to flex and move over the needle assembly, permitting the deformable base to move the enlarged head of the needle downward until further movement of the enlarged head is blocked by the needle assembly. With the enlarged needle head blocked by the needle assembly, continued force at the plunger causes the deformable base to move around the enlarged needle head. As the deformable base moves around the needle assembly, the enlarged needle head begins to protrude from the deformable base and come into contact with the web on the boot of the plunger. Continued force causes the enlarged needle head to tear the web of the boot, positioning the enlarged needle head just inside a hollow portion of the plunger. The torn portion of the web creates a flap just inside the hollow plunger. As the plunger moves the deformable base still further, the enlarged needle head looses contact with the deformable base, which triggers a release of energy from the energy storage means in the passageway, projecting the needle with its enlarged head into the hollow portion of the plunger. Once inside the plunger, the needle is trapped by its enlarged head behind a flexible catch within the plunger. Final movement of the plunger causes the plunger to become substantially locked in the barrel and causes a liquid tight seal to be created between the plunger and the syringe body. A closing member placed on the front of the needle assembly completely seals the syringe to prevent residual fluids from escaping. Completion of the needle retraction also automatically highlights an indicia such as a biohazard label which alerts persons handling the device that the syringe has been used and represents a potential biohazard.
In an alternative embodiment of the syringe according to this invention, a barrel, needle assembly, needle head, and deformable base of different structures than above are utilized wherein the deformable base is positioned between sacrificial supports in the needle assembly and an internal wedged end of the barrel. Upon completion of injection, the boot contacts the deformable base, and upon application of force at the plunger, moves the base downward, initially breaking the liquid tight seal between the base and the barrel. Continued application of force causes the sacrificial supports within the needle assembly to sever, permitting the deformable base to move the enlarged head of the needle downward until further movement of the enlarged head is blocked by the passageway in the needle assembly. With the enlarged needle head blocked by the passageway, continued force at the plunger causes the deformable base to move around the enlarged needle head. As the deformable base moves forward, the enlarged needle head begins to protrude from the deformable base and come into contact with a thin, rupturable web on the boot of the plunger. Continued force causes the enlarged needle head to penetrate the web of the boot, positioning the enlarged needle head just inside a hollow portion of the plunger. As the plunger moves the deformable base still further, the enlarged needle head looses contact with the deformable base, which triggers a release of energy from the energy storage means in the passageway, projecting the needle into the hollow portion of the plunger. Once inside the plunger, the needle is trapped by its enlarged head within the plunger. Final movement of the plunger causes the plunger to become captured in the barrel at the back of the syringe.